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Diffstat (limited to 'microkernel')
| -rw-r--r-- | microkernel/mach/deficiencies.mdwn | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/microkernel/mach/deficiencies.mdwn b/microkernel/mach/deficiencies.mdwn index 0c342e20..b7927210 100644 --- a/microkernel/mach/deficiencies.mdwn +++ b/microkernel/mach/deficiencies.mdwn @@ -15,6 +15,23 @@ License|/fdl]]."]]"""]] # Deficiencies +Mach is a first generational microkernel, and many of mach's implementations are poor. +The result is a complicated code base with many issues. Problems include resource accounting, +scheduling, and too many features inside the kernel. Another problem is mach's IPC is +too flexible and has numerous features. The more features and complex the message passing is, +the slower performance becomes. Mach's IPC ought to be simple enough to maximize performance. + +Mach also doesn't support any read-ahead techniques, so its I/O performance suffers. +Read ahead will have to be implemented inside the kernel. + +There are many optimizations that can be done: + +We could easily get rid of the ihash library making the message provide the address of +the object associated to a receive right, so the only real indirection is the capability, +like in other systems, and yes, buffering adds a bit of complexity. Another example is +merging structures to improve locality or having rights close to their target port, +when there are only a few. This would increase cache efficiency. + ## IRC, freenode, #hurd, 2012-06-29 <henrikcozza> I do not understand what are the deficiencies of Mach, the @@ -266,6 +283,19 @@ License|/fdl]]."]]"""]] # X15 +X15 is an in-development hurd-like operating system. It's developer, Richard +Braun, decided that GNU/Hurd running on the mach microkernel has many short-comings. +Namely to make the Hurd "better" required deep changes to gnumach. He decided to start +a new project from scratch. Instead of running the Hurd on top of gnumach, he started +building his own microkernel: X15, which is like gnumach. Originally he had intended +to port the gnuhurd to run ontop of X15, but X15 has since made some design decisions +that make porting the Hurd to run on top of X15 very unlikely. Occasionally some X15 +code can be used on the GNU/Hurd, which is what happened with the buddy allocator. + +Currently X15 is a real-time microkernel with low-level performance monitoring system, +local atomic operations, lockless synchronization, RCU, and it can scale well on any 32-bit, +64-bit target. It currently runs on x86 and ARM processors, but it lacks userspace support. + ## IRC, freenode, #hurd, 2012-09-04 <braunr> it was intended as a mach clone, but now that i have better |